|Publication number||US5008593 A|
|Application number||US 07/553,929|
|Publication date||Apr 16, 1991|
|Filing date||Jul 13, 1990|
|Priority date||Jul 13, 1990|
|Publication number||07553929, 553929, US 5008593 A, US 5008593A, US-A-5008593, US5008593 A, US5008593A|
|Inventors||LaVerne A. Schlie, Robert D. Rathge|
|Original Assignee||The United States Of America As Represented By The Secretary Of The Air Force|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (11), Referenced by (50), Classifications (12), Legal Events (6)|
|External Links: USPTO, USPTO Assignment, Espacenet|
The invention described herein may be manufactured and used by or for the government of the U.S. for all governmental purposes without the payment of any royalty.
The invention described herein is related to copending application Ser. No. 07/553,928 filed 07/13/90, entitled LIQUID COOLANT FOR HIGH POWER MICROWAVE EXCITED PLASMA TUBES.
The present invention relates generally to systems for generating microwave excited plasma discharges, and more particularly to systems for effectively cooling high power microwave plasma tubes.
In the copending application, use of liquid dimethyl polysiloxane as a coolant of high power, microwave (2450 MHz) excited plasmas useful as high intensity ultraviolet (UV), visible and infrared (IR) lamps was demonstrated. Liquid dimethyl polysiloxane used in coolant system structures of suitable configuration exhibited high UV and visible transmission, low microwave absorption at the desired microwave operating frequency, ability to withstand high cw or pulsed UV and visible fluences, non-toxicity and non-flammability, large IR absorption and desirable physical chemistry properties (low viscosity, low vapor pressure, large heat capacity, high thermal conductivity). The teachings of the copending application and background material presented therein are incorporated herein by reference.
Existing UV lamp systems that incorporate microwave excited plasmas mounted in a reflector assembly generally require large air cooling capacity (e.g., 240 cfm) and a.c. (60 Hz) power to the magnetrons. The present invention solves this deficiency in prior art structures by providing a coolant system in a reflector assembly for a microwave excited plasma incorporating liquid dimethyl polysiloxane as coolant. The cooling system provided by the invention obviates the need for large gas flow cooling capability for the plasma tube, can accommodate any reflector geometry (e.g. elliptical, circular, spherical, parabolic or involute), and allows higher (viz., about two times) power loadings to be accomplished for the plasmas.
It is therefore a principal object of the invention to provide a coolant system for high power microwave excited UV lamps utilizing liquid dimethyl polysiloxane in a reflector assembly capable of focusing output radiation.
It is another object of the invention to provide transverse or coaxial liquid cooling to a microwave excited plasma tube in a UV, visible or IR reflector assembly of any geometry.
These and other objects of the invention will become apparent as a detailed description of representative embodiments proceeds.
In accordance with the foregoing principles and objects of the invention, in a high power microwave excited plasma system including a microwave energy source operatively coupled to a plasma tube for generating a plasma within the tube, a gaseous medium within the tube for supporting a plasma and a reflector for focusing radiation emitted from the tube, an improved cooling system for the tube is provided which comprises a jacket surrounding the tube and defining a passageway therearound, a source of liquid dimethyl polysiloxane, and a circulator for conducting the liquid dimethyl polysiloxane through the passageway in heat exchange relationship with the tube.
The invention will be more clearly understood from the following detailed description of representative embodiments thereof read in conjunction with the accompanying drawings wherein:
FIG. 1 is a schematic sectional view of a microwave excited plasma tube mounted inside an elliptical reflector; and
FIG. 2 is a schematic sectional view of the FIG. 1 plasma tube coupled to a microwave source and cooled according to the invention.
Referring now to FIGS. 1 and 2, shown therein are schematic sectional views of a microwave excited plasma tube 11 mounted inside an elliptical reflector 13. Plasma tube 11 may comprise an electrodeless quartz lamp coupled to a microwave source 15 and cooled according to the teachings of the invention. Microwave source 15 (usually about 2450 MHz) provides continuous or pulsed excitation to plasma tube 11, and is operatively coupled into plasma tube 11 by way of waveguides 17, 18 and slotted couplers 19, 20 defined in reflector 13 between waveguides 17, 18 and housing 21 for containing plasma tube 11. Tube 11 is mounted inside elliptical reflector 13 at the focus of an ellipsoid defined by reflector 13, and is filled with suitable gaseous plasma medium such as xenon, mercury, argon, halides (gaseous or solid), boron chloride or mercury vapor/gas mixtures at pressures of about 10-3 to 10 atm. Tube 11 may be of any suitable length, viz., about 2 to 100 cm, and inner diameter, viz., about 0.01 to 10 cm, limited only by the power of microwave source 15, a tube operated in demonstration of the invention being about 25 cm in length and 1 cm ID. Reflector 13 comprises suitable metallic reflective material such as aluminum, copper, gold or multi-stack dielectrics, and functions to selectively focus ultraviolet (UV), visible or infrared (IR) radiation 23 emitted from plasma tube 11. It is noted that other geometrical configurations for reflector 13 may be used in contemplation of the invention, such as parabolic, involute or spherical shapes, the same not considered limiting of the invention. Plasma tube 11 may be resiliently mounted at spring 25 in a non-compressive manner within housing 21 between aluminum posts 27 and quartz canes 28. Quartz cooling jacket 31 surrounds tube 11 and defines passageway 32 for the flow of liquid dimethyl polysiloxane coolant from source 33. Aluminum tubes connected to respective ends of jacket 31 define inlet 35 and outlet 36 for conducting coolant along passageway 32 in heat exchange relationship with tube 11. Jacket 31 is normally a few millimeters larger in diameter than tube 11 allowing a radial thickness for passageway 32 of at least 1-2 mm. Components of the demonstration system for containing and conducting the liquid dimethyl siloxane comprised aluminum in accordance with teachings of the cross reference. The liquid dimethyl polysiloxane was circulated utilizing a Neslab HX750 cooler and was kept in the temperature range of 20°-50° C. Liquid dimethyl polysiloxane has a very low microwave absorption value (tan δ=ε "/ε'=3.5×10-4 or ε"=5.43×10-4), absorbs negligible microwave energy (≦0.2 watts per cm per KW incident power) and is transparent to UV. As suggested in the cross reference, dimethyl polysiloxane remains a clear liquid from -73° to 260° C. Tube 11 and jacket 31 comprises quartz or other material transparent to UV such as sapphire, beryllium oxide, magnesium fluoride or lithium fluoride. An rf screen/UV window 38 (optional) may be disposed across reflector 13 to prevent leakage of microwave radiation and simultaneously to transmit the UV and visible output radiation 23 of tube 11.
The structure of FIGS. 1, 2 defines a coaxial configuration for cooling tube 11 according to the invention. However, it is noted that alternative structure incorporating transverse coolant flow could be assembled by one skilled in the art guided by these teachings, the transverse cooling configuration considered to be within the scope hereof.
The coolant system provided by the invention exhibits low microwave absorption (<0.2 watts per cm absorbed per KW incident microwave power at 2450 Mhz) which allows much higher volumetric power loadings (≅300 watts/cm3 or 5.4 KW in a volume of 20 cm3), than is attainable in conventional systems, and eliminates noise and mechanical vibrations produced by the high gas flow required to cool a conventional plasma tube. Tube performance varied somewhat with the temperature of the coolant. The coolant is substantially transparent to the intense UV radiation from the plasma tube, absorbs a significant portion of the radiated heat (IR radiation, λ>1.0 micron) from the plasma tube and exhibits low microwave absorption.
The invention therefore provides a coolant system for high power microwave excited plasma lamps utilizing liquid dimethyl polysiloxane in a reflector assembly capable of focusing output radiation. It is understood that modifications to the invention may be made as might occur to one with skill in the field of the invention within the scope of the appended claims. All embodiments contemplated hereunder which achieve the objects of the invention have therefore not been shown in complete detail. Other embodiments may be developed without departing from the spirit of the invention or from the scope of the appended claims.
|Cited Patent||Filing date||Publication date||Applicant||Title|
|US3401302 *||Nov 1, 1965||Sep 10, 1968||Humphreys Corp||Induction plasma generator including cooling means, gas flow means, and operating means therefor|
|US3641389 *||Nov 5, 1969||Feb 8, 1972||Varian Associates||High-power microwave excited plasma discharge lamp|
|US3876901 *||Dec 3, 1973||Apr 8, 1975||Varian Associates||Microwave beam tube having an improved fluid cooled main body|
|US3885984 *||Dec 18, 1973||May 27, 1975||Gen Electric||Methyl alkyl silicone thermoconducting compositions|
|US4045119 *||Jun 13, 1975||Aug 30, 1977||Laser Bioapplications||Flexible laser waveguide|
|US4500996 *||Mar 31, 1982||Feb 19, 1985||Coherent, Inc.||High power fundamental mode laser|
|US4617667 *||Oct 28, 1983||Oct 14, 1986||P.R.C., Ltd.||Gas laser tube assembly|
|US4715039 *||Jul 12, 1985||Dec 22, 1987||Spectra-Physics, Inc.||Internal resonator water cooled ion laser|
|US4737678 *||Aug 5, 1986||Apr 12, 1988||Pioneer Electronic Corporation||Cooling system for projection television receiver|
|US4868450 *||Feb 22, 1989||Sep 19, 1989||Colterjohn Jr Walter L||Radiation device|
|US4933650 *||Feb 22, 1989||Jun 12, 1990||Hitachi, Ltd.||Microwave plasma production apparatus|
|Citing Patent||Filing date||Publication date||Applicant||Title|
|US5144199 *||Jan 4, 1991||Sep 1, 1992||Mitsubishi Denki Kabushiki Kaisha||Microwave discharge light source device|
|US5227698 *||Mar 12, 1992||Jul 13, 1993||Fusion Systems Corporation||Microwave lamp with rotating field|
|US5235251 *||Aug 9, 1991||Aug 10, 1993||The United States Of America As Represented By The Secretary Of The Air Force||Hydraulic fluid cooling of high power microwave plasma tubes|
|US5301203 *||Sep 23, 1992||Apr 5, 1994||The United States Of America As Represented By The Secretary Of The Air Force||Scalable and stable, CW photolytic atomic iodine laser|
|US5425044 *||Jul 22, 1994||Jun 13, 1995||The United States Of America As Represented By The Secretary Of The Air Force||Compact, burst mode, pulsed, high energy, blowdown flow photolytic atomic iodine laser|
|US5528618 *||Nov 19, 1993||Jun 18, 1996||The United States Of America As Represented By The Secretary Of The Air Force||Photolytic iodine laser system with turbo-molecular blower|
|US5568015 *||Feb 16, 1995||Oct 22, 1996||Applied Science And Technology, Inc.||Fluid-cooled dielectric window for a plasma system|
|US5625259 *||Feb 16, 1995||Apr 29, 1997||Applied Science And Technology, Inc.||Microwave plasma applicator with a helical fluid cooling channel surrounding a microwave transparent discharge tube|
|US5802093 *||May 22, 1996||Sep 1, 1998||Townsend; Sallie S.||Continuous wave photolytic iodine laser|
|US5892328 *||Jun 27, 1997||Apr 6, 1999||Applied Komatsu Technology Inc.||High-power, plasma-based, reactive species generator|
|US5895548 *||Mar 29, 1996||Apr 20, 1999||Applied Komatsu Technology, Inc.||High power microwave plasma applicator|
|US6026762 *||Apr 23, 1997||Feb 22, 2000||Applied Materials, Inc.||Apparatus for improved remote microwave plasma source for use with substrate processing systems|
|US6039834 *||Mar 5, 1997||Mar 21, 2000||Applied Materials, Inc.||Apparatus and methods for upgraded substrate processing system with microwave plasma source|
|US6087774 *||Oct 29, 1997||Jul 11, 2000||Kabushiki Kaisha Toshiba||Non-electrode discharge lamp apparatus and liquid treatment apparatus using such lamp apparatus|
|US6230652||Jan 11, 2000||May 15, 2001||Applied Materials, Inc.||Apparatus and methods for upgraded substrate processing system with microwave plasma source|
|US6271148||Oct 13, 1999||Aug 7, 2001||Applied Materials, Inc.||Method for improved remote microwave plasma source for use with substrate processing system|
|US6274058||Jul 2, 1999||Aug 14, 2001||Applied Materials, Inc.||Remote plasma cleaning method for processing chambers|
|US6284051 *||May 27, 1999||Sep 4, 2001||Ag Associates (Israel) Ltd.||Cooled window|
|US6333509||Jul 9, 1997||Dec 25, 2001||Lumpp & Consultants||Electromagnetic radiation transmitter/reflector device, apparatus and process implementing such a device|
|US6361707||Sep 12, 2000||Mar 26, 2002||Applied Materials, Inc.||Apparatus and methods for upgraded substrate processing system with microwave plasma source|
|US6388226||Feb 10, 2000||May 14, 2002||Applied Science And Technology, Inc.||Toroidal low-field reactive gas source|
|US6486431||Sep 12, 2000||Nov 26, 2002||Applied Science & Technology, Inc.||Toroidal low-field reactive gas source|
|US6495800||Jan 5, 2001||Dec 17, 2002||Carson T. Richert||Continuous-conduction wafer bump reflow system|
|US6552296||Sep 17, 2001||Apr 22, 2003||Applied Science And Technology, Inc.||Toroidal low-field reactive gas source|
|US6559408||May 10, 2002||May 6, 2003||Applied Science & Technology, Inc.||Toroidal low-field reactive gas source|
|US6664497||May 10, 2002||Dec 16, 2003||Applied Science And Technology, Inc.||Toroidal low-field reactive gas source|
|US6815633||Mar 12, 2001||Nov 9, 2004||Applied Science & Technology, Inc.||Inductively-coupled toroidal plasma source|
|US7094993||Oct 19, 2004||Aug 22, 2006||Radiant Technology Corp.||Apparatus and method for heating and cooling an article|
|US7161112||Oct 20, 2003||Jan 9, 2007||Mks Instruments, Inc.||Toroidal low-field reactive gas source|
|US7166816||May 3, 2004||Jan 23, 2007||Mks Instruments, Inc.||Inductively-coupled torodial plasma source|
|US7170036||Dec 16, 2002||Jan 30, 2007||Radiant Technology Corporation||Apparatus and method for heating and cooling an article|
|US7541558||Dec 11, 2006||Jun 2, 2009||Mks Instruments, Inc.||Inductively-coupled toroidal plasma source|
|US7906911 *||May 1, 2008||Mar 15, 2011||Fusion Uv Systems, Inc.||Luminaire assembly having a bonded reflector cavity for supporting an ultra-violet lamp|
|US8124906||Jul 29, 2009||Feb 28, 2012||Mks Instruments, Inc.||Method and apparatus for processing metal bearing gases|
|US8779322||Dec 23, 2011||Jul 15, 2014||Mks Instruments Inc.||Method and apparatus for processing metal bearing gases|
|US9433070||Dec 11, 2014||Aug 30, 2016||Kla-Tencor Corporation||Plasma cell with floating flange|
|US20040079287 *||Oct 20, 2003||Apr 29, 2004||Applied Science & Technology, Inc.||Toroidal low-field reactive gas source|
|US20070145018 *||Dec 11, 2006||Jun 28, 2007||Mks Instruments, Inc.||Inductively-coupled toroidal plasma source|
|US20090273932 *||May 1, 2008||Nov 5, 2009||Fusion Uv Systems, Inc.||Bonded single-piece ultra-violet lamp luminaire for microwave cavities|
|US20090288772 *||Jul 29, 2009||Nov 26, 2009||Mks Instruments, Inc.||Method and Apparatus for Processing Metal Bearing Gases|
|US20100215541 *||Oct 11, 2007||Aug 26, 2010||Ralf Spitzl||Device and method for producing high power microwave plasma|
|DE102006022970B3 *||May 11, 2006||Nov 22, 2007||Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V.||UV-Lichtquelle|
|EP0914672A1 *||Jan 24, 1997||May 12, 1999||Fusion Lighting, Inc.||Microwawe lamp with multi-purpose rotary motor|
|EP0914672A4 *||Jan 24, 1997||May 12, 1999||Title not available|
|EP1262091A1 *||Dec 22, 2000||Dec 4, 2002||Fusion Uv Systems, Inc.||Lamp with self-constricting plasma light source|
|EP1262091A4 *||Dec 22, 2000||Sep 10, 2003||Fusion Uv Sys Inc||Lamp with self-constricting plasma light source|
|WO1998001700A2 *||Jul 9, 1997||Jan 15, 1998||Lumpp & Consultants||Electromagnetic radiation transmitter/reflector device, apparatus and method therefor|
|WO1998001700A3 *||Jul 9, 1997||May 22, 1998||Christian Lumpp||Electromagnetic radiation transmitter/reflector device, apparatus and method therefor|
|WO2008046551A1 *||Oct 11, 2007||Apr 24, 2008||Iplas Innovative Plasma Systems Gmbh||Device and method for producing high power microwave plasma|
|WO2015089424A1 *||Dec 12, 2014||Jun 18, 2015||Kla-Tencor Corporation||Plasma cell with floating flange|
|U.S. Classification||315/39, 313/22, 313/36|
|International Classification||H05H1/46, H01J65/04, H01J7/26|
|Cooperative Classification||H05H1/46, H01J65/044, H01J7/26|
|European Classification||H05H1/46, H01J65/04A1, H01J7/26|
|Apr 29, 1993||AS||Assignment|
Owner name: UNITED STATES OF AMERICA, THE, AS REPRESENTED BY T
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNORS:SCHLIE, LEVERNE A.;RATHGE, ROBERT D.;REEL/FRAME:006495/0949
Effective date: 19930316
|Sep 12, 1994||FPAY||Fee payment|
Year of fee payment: 4
|May 4, 1998||FPAY||Fee payment|
Year of fee payment: 8
|Oct 30, 2002||REMI||Maintenance fee reminder mailed|
|Apr 16, 2003||LAPS||Lapse for failure to pay maintenance fees|
|Jun 10, 2003||FP||Expired due to failure to pay maintenance fee|
Effective date: 20030416